DESCRIPTION (APPLICANT'S ABSTRACT): The vertex-recorded midlatency auditory evoked P50 potential is a measure of the output of the reticular activating system (RAS). This rapidly-habituating, sleep state-dependent potential is present during waking and paradoxical sleep but absent during slow-wave sleep, i.e. is present only during cortical EEC "desynchronization" or arousal. The amplitude of the P50 potential is decreased in narcolepsy and autism, that is, in diseases in which there appears to be downregulation of the output of the RAS. Using a paired stimulus paradigm, sensory gating of the P50 potential (the ability to habituate to or "filter" repetitive stimuli) can be assessed. There is a deficit in sensory gating of this potential in schizophrenia and anxiety disorders, that is, it diseases in which there appears to be an upregulation of the output of the RAS. We have preliminary data suggesting that electroacupuncture (EA) applied at three specific points may modulate the manifestation of the P50 potential. In a small number of subjects, we found that stimulation using needles was as effective a., stimulation using surface electrodes (an important innovation in the therapeutic use of EA), that stimulation a low frequencies may be more efficacious than stimulation at medium or high frequencies, that stimulation at only two of these points or three unrelated "control" points may be ineffective, and that using multiple episodes o1 stimulation may have additive effects in modulating P50 potential amplitude, suggesting important clinical applications in a number of disorders. The proposed feasibility studies will use larger samples of subjects comparing male vs female, and Caucasian vs African-American, populations to determine with sufficient power that a statistically significant effect on the amplitude of the P50 potential is present or absent under each of these experimental conditions. In addition, sensory gating of the P50 potential will be assessed for each experiments condition, allowing predictions of the effects of such treatment on either the initial manifestation (amplitude o1 the P50 potential induced by the first stimulus of a pair) or the sensory gating (ratio of the amplitudes of the PM potentials induced by the paired stimuli) of this non-invasive measure of RAS function. It may be possible in the future, to use this novel treatment methodology as an adjunct/replacement therapy for disorders of arousal, especially if the effects of multiple episodes of stimulation can be found to affect amplitude and/or sensory gating of the P50 potential for prolonged periods of time. However, the optimal stimulation sites and paradigms muse be identified and proven effective, first, in control populations, and later, in pathological populations.